The present invention relates to the scheduling of movement of plural units through a complex movement defining system, and in the embodiment disclosed, to the scheduling of the movement of freight trains over a railroad system and specifically to congestion management.
Systems and methods for scheduling the movement of trains over a rail network have been described in U.S. Pat. Nos. 6,154,735, 5,794,172, and 5,623,413, the disclosure of which is hereby incorporated by reference.
As disclosed in the referenced patents and applications, the complete disclosure of which is hereby incorporated herein by reference, railroads consist of three primary components (1) a rail infrastructure, including track, switches, a communications system and a control system; (2) rolling stock, including locomotives and cars; and, (3) personnel (or crew) that operate and maintain the railway. Generally, each of these components are employed by the use of a high level schedule which assigns people, locomotives, and cars to the various sections of track and allows them to move over that track in a manner that avoids collisions and permits the railway system to deliver goods to various destinations.
As disclosed in the referenced applications, a precision control system includes the use of an optimizing scheduler that will schedule all aspects of the rail system, taking into account the laws of physics, the policies of the railroad, the work rules of the personnel, the actual contractual terms of the contracts to the various customers and any boundary conditions or constraints which govern the possible solution or schedule such as passenger traffic, hours of operation of some of the facilities, track maintenance, work rules, etc. The combination of boundary conditions together with a figure of merit for each activity will result in a schedule which maximizes some figure of merit such as overall system cost.
As disclosed in the referenced applications, and upon determining a schedule, a movement plan may be created using the very fine grain structure necessary to actually control the movement of the train. Such fine grain structure may include assignment of personnel by name, as well as the assignment of specific locomotives by number, and may include the determination of the precise time or distance over time for the movement of the trains across the rail network and all the details of train handling, power levels, curves, grades, track topography, wind and weather conditions. This movement plan may be used to guide the manual dispatching of trains and controlling of track forces, or may be provided to the locomotives so that it can be implemented by the engineer or automatically by switchable actuation on the locomotive.
The planning system is hierarchical in nature in which the problem is abstracted to a relatively high level for the initial optimization process, and then the resulting course solution is mapped to a less abstract lower level for further optimization. Statistical processing is used at all levels to minimize the total computational load, making the overall process computationally feasible to implement. An expert system is used as a manager over these processes, and the expert system is also the tool by which various boundary conditions and constraints for the solution set are established. The use of an expert system in this capacity permits the user to supply the rules to be placed in the solution process.
Currently, a dispatcher's view of the controlled railroad territory can be considered myopic. Dispatchers view and process information only within their own control territories and have little or no insight into the operation of adjoining territories, or the railroad network as a whole. Current dispatch systems simply implement controls as a result of the individual dispatcher's decisions on small portions of the railroad network and the dispatchers are expected to resolve conflicts between movements of objects on the track (e.g. trains, maintenance vehicles, survey vehicles, etc.) and the available track resource limitations (e.g. limited number of tracks, tracks out of service, consideration of safety of maintenance crews near active tracks) as they occur, with little advanced insight or warning.
Congestion inevitably occurs in the routing of trains and is a significant problem. Examples of congestion include track block, train ahead without authority to move, unidentified track occupancy, train needs additional motive power, train nearing the end of a plan that is truncated because of a planning exception, and train ahead in a safe place.
The routing of trains into a congested area tends to exacerbate the congestion and may result in deadlock. When a train is routed too far into congestion, options for resolving the congestion are reduced. For example, if a track is blocked for a mishap and trains are routed as closely as possible to the blockage, some of the routes to reach the mishap and to route trains around it are unavailable.
Because the delay in the movement of trains is subject to cost constraints including contract penalties, the tendency of dispatchers is to continue to push trains through an area as rapidly as possible, advancing their movement along the line of road whenever possible, and treating the resulting congestion as a track availability problem to be solved through the assignment of track resources to create alternative routes through the congested area. The movement planners used by dispatchers in adjacent territories are often completely independent of each other and uninformed as to the status of the tracks in adjacent territories. As a result, dispatchers in uncongested areas may continue to send trains into a congested area in the adjacent territory.
The present application relates to the maximizing of the throughput of trains in the overall system at the expense of the movement of trains over smaller sections of track. This typically results in the delay of trains outside an area of congestion in order to provide time to clear the congestion. One major advantage of such delay is that the alternative routes may be kept open thus facilitating the clearance of the congestion and the overall efficiency of the system.
It is accordingly an object of the present invention to reduce congestion and avoid deadlock by the management of the entry of trains into a congested area. In part, this is accomplished by the cessation of the automatic routing of trains once congestion is detected or anticipated. If possible, it is desirable to hold trains nearing the congested area (or area projected to become congested) in safe areas, i.e., areas where other trains may pass.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.